The proposed studies will be directed towards elucidating mechanisms of trophic interactions between motor nerves and skeletal muscles; learning more about sprouting of peripheral nerves; and studying the mechanisms of neuromuscular disorders including myasthenia gravis. We will carry out studies of the effects of blockade of various components of cholinergic transmission on several properties of muscle that are regulated by the nerves. We will explore the role of acetylcholine receptors in eliciting sprouting of motor nerve, and examine the effect of other factors on nerve sprouting. Finally, we will examine various aspects of humoral and cellular immune mechanisms in the initiation and maintenance of the myasthenic state in man and animal.